Thought this Document might be helpful for people doing any sort of Word document merge functions within Netsuite.    

The linked document is something I created for my company with most of the common fields we might use for Mail merge documents.  It helps me, as an administrator, to determine what fields are going to work when a user requests a new mail merge document. 

I uploaded the document to Netsuite as a template and perform letter merges on leads, customers or contacts to determine what fields I will need to put into a new template.  I then just copy the appropriate merge field from this document into my new templates so I dont need to create a NEW mail merge document in MS-Word.